1. Field of the Invention
The preset invention relates to a robot controller for moving a robot based on a force applied to the robot, and relates to a robot system including the robot and the robot controller.
2. Description of the Related Art
As an operation method for moving a robot by applying a force to the robot, or a method for moving a robot by applying a force to the robot so as to teach a position, direct teaching is well known. In direct teaching, by directly guiding the robot by applying a force to the robot in a desired moving direction, the robot can be moved to a desired position and/or orientation on an orthogonal coordinate system.
As relevant prior art documents, JP S56-085106 A discloses a method for moving the position and orientation of a front end of a robot arm, based on a signal generated by a force detector when a manual operation part attached to the front end of the robot arm is operated.
Further, JP H06-250728 A discloses a direct teaching device for a robot, wherein a force sensor arranged on the robot detects a force by a human applied to an end effector, and a robot arm is guided only in a direction determined by an operation direction setting means, when the motion of the robot arm is to be controlled based on a force signal obtained by the force sensor.
In the method of JP S56-085106 A, the position and/or orientation of the front end of the robot on the orthogonal coordinate system are moved in response to the force. In this regard, depending on a setting of responsiveness of the force control or a way of movement, the motion for changing the orientation may be unstable. Further, JP S56-085106 A does not describe a method or means for moving the position of each axis during the direct teaching.
On the other hand, it could be understood that the device of JP H06-250728 A is configured to limit the direction of movement of the robot in relation to a direction regarding the position or orientation of the front end of the robot on a Cartesian coordinate system, when the robot is moved by the direct teaching, and move the robot only in the limited direction so as to improve operability of the robot. However, JP H06-250728 A does not describe a method for stably changing the orientation of the robot or stably moving the position of each axis.